INTRODUCTION: HIV self-testing (HIVST) is a useful strategy to promote HIV testing among key populations. This study aimed to understand HIV testing behaviours among men who have sex with men (MSM) and specifically how HIVST was used during the coronavirus disease 2019 (COVID-19) measures in China when access to facility-based testing was limited. METHODS: An online cross-sectional study was conducted to recruit men who have sex with men (MSM) in China from May to June of 2020, a period when COVID-19 measures were easing. Data on socio-demographic characteristics, sexual behaviours and HIV testing in the three months before and during COVID-19 measures (23 January 2020) were collected. Chi-square test and logistic regression were used for analyses. RESULTS: Overall, 685 MSM were recruited from 135 cities in 30 provinces of China, whose mean age was 28.8 (SD: 6.9) years old. The majority of participants self-identified as gay (81.9%) and had disclosed their sexual orientation (66.7%). In the last three months, 69.6% ever had sex with men, nearly half of whom had multiple sexual partners (47.2%). Although the overall HIV testing rates before and during COVID-19 measures were comparable, more MSM self-tested for HIV during COVID-19 measures (52.1%) compared to before COVID-19 measures (41.6%, p = 0.038). Fewer MSM used facility-based HIV testing during COVID-19 measures (42.9%) compared to before COVID-19 measures (54.1%, p = 0.038). Among 138 facility-based testers before COVID-19 measures, 59.4% stopped facility-based testing during COVID-19 measures. Among 136 self-testers during COVID-19 measures, 58.1% had no HIV self-testing before COVID-19 measures. Multivariable logistic regression showed that having sex with other men in the last three months (adjusted odds ratio, aOR = 2.04, 95% CI: 1.38 to 3.03), self-identifying as gay (aOR = 2.03, 95% CI: 1.31 to 3.13), ever disclosing their sexual orientation (aOR = 1.72, 95% CI: 1.19 to 2.50) and tested for HIV in three months before COVID-19 measures (aOR = 4.74, 95% CI: 3.35 to 6.70) were associated with HIV testing during COVID-19 measures. CONCLUSIONS: Facility-based HIV testing decreased and HIVST increased among MSM during COVID-19 measures in China. MSM successfully accessed HIVST as substitute for facility-based testing, with no overall decrease in HIV testing rates.